Green’s Dictionary of Slang

humpty adj.1

[hump n.1 (1)]

irritated, tetchy.

[UK]B. Naughton Alfie Darling 143: I was behaving a bit humpty with her for a start, sort of grunting instead of talking.
[Scot]I. Welsh Trainspotting 111: Humpty cunt. Everything that red-headed cunt’s shite at’s ir arseholes.